By Peter Luyckx
The findings support the “hygiene hypothesis” that holds that children who are exposed to fewer infections while they are young are at higher risk of developing autoimmune diseases, such as asthma, later in life, said Dr. Marisa D’Angeli, a medical epidemiologist with the Washington State Department of Health and lead author of the study.
Unlike type 2, or adult-onset, diabetes, which is linked to obesity and poor nutrition and is more common among the poor, type 1 diabetes is an autoimmune disease in which a misguided immune system destroys the body’s insulin-producing cells of the pancreas.
Because type 1 diabetes tends to strike the young, it’s often called “juvenile-onset” diabetes.
In the new study, researchers from the Washington State Department of Health, the University of Washington and Israel reviewed medical records of Washington state children who had been diagnosed with type 1 diabetes and compared them with a matched group that had not.
They found that factors related to a mother’s lower socioeconomic status—such as inadequate prenatal care, using Medicaid insurance, not having finished high school, or being unmarried—were actually associated with lower rates of childhood-onset diabetes, not higher ones.
The hygiene hypothesis, well-known as an explanation for rising rates of asthma in affluent societies, holds that improved standards of living have reduced exposure to childhood infections, which, in turn, alters the development of the immune system in children to make them more susceptible to autoimmune diseases.
Children born to less affluent moms, on the other hand, are more likely to be exposed to infections because they are more likely to live in crowded living conditions and attend day care. When infected, they are less likely to have access to medical care so infections are not treated as quickly.
This increased exposure to infection, according to the hygiene hypothesis, actually helps the immune system develop normally, reducing the risk of developing an autoimmune disease.
More siblings, more germs, healthier immune systems
Another finding of the study supported the hygiene hypothesis: first-born children were more likely to develop type 1 diabetes than were children who had siblings, perhaps, says D’Angeli, “because they have less exposure to childhood infections, like colds and viruses.”
“But what can you take from that?” she quips. “Don’t have a first-born child?”
D’Angeli shies away from making specific recommendations on how to strike an appropriate hygiene balance. “Diabetes is a very complicated disease. Our study just adds a little bit of information to the puzzle,” she cautions.
Still, the hygiene hypothesis seems to suggest that extremely “germophobic” parents can go too far in trying to protect their children from every cold and sniffle and speck of dirt.
One way moms can try to make a difference is by achieving and maintaining a healthy weight.
The researchers found a higher risk of Type 1 diabetes for children of obese mothers (with a body mass index of 30 or higher) and of mothers who weighed more than 200 pounds before they got pregnant.
This may be because taxing the fetus’ pancreas by overeating during pregnancy could damage the developing organ, increasing the child’s risk of developing diabetes, a theory called the overload hypothesis.
Researchers hope that by identifying the environmental factors behind type 1 diabetes, they will find ways to reverse the worldwide rise in cases. “The more we learn,” D’Angeli said, “the better we are prepared to prevent and treat it.”
Peter Luyckx is a contributing writer to Seattle Local Health Guide and to Flip the Media. He is a graduate student in the Master of Communication in Digital Media program at the University of Washington and can be followed on Twitter @peterlux.
To learn more:
- Read the paper Environmental Factors Associated With Childhood-Onset Type 1 Diabetes Mellitus: An Exploration of the Hygiene and Overload Hypotheses (Free.) PDF version.
- For a list of current type 1 diabetes research studies in our region, visit the Northwest Chapter of the Juvenile Diabetes Research Foundation.
Marisa A. D’Angeli, MD, MPH; Eugene Merzon, MD, MPH; Luisa F. Valbuena, DDS, MPH; David Tirschwell, MD, MSc; Carolyn A. Paris, MD, MPH; Beth A. Mueller, DrPH. Environmental Factors Associated With Childhood-Onset Type 1 Diabetes Mellitus: An Exploration of the Hygiene and Overload Hypotheses. Arch Pediatr Adolesc Med. 2010;164(8):732-738. doi:10.1001/archpediatrics.2010.115